PROJECT SUMMARY/ABSTRACT As a result of the emerging national opiate crisis, child welfare agencies have experienced an increase in the number of children in foster care as parental substance use puts children at greater risk of maltreatment. Child welfare agencies are well positioned to help identify and connect parents with substance use treatment. Promising evidence-based interventions exist that that emphasize brief screening, linkage to treatment, and integration across child welfare and substance use treatment systems, including the START model (Sobriety Treatment and Recovery Teams). Successful implementation of START depends on strong collaboration between substance use treatment and child welfare systems. To improve implementation and future scale-up of START, there is a need for effective collaborative strategies that support integration of county child welfare and substance use treatment systems, which has potential to benefit those with highly complex substance use service needs involved in other health and human service systems. Our long-term goal is to test the effectiveness of collaborative strategies that promote the adoption, implementation, and sustainment of START and other cross-system treatment innovations. This study begins to address this goal by developing a multifaceted and feasible decision support guide for collaborative strategy selection for executive leaders. To do so, we will conduct a multisite longitudinal, mixed methods study that builds on the Ohio START project, a naturally occurring implementation initiative in 17 predominantly rural southern-Ohio counties funded by the Ohio Attorney General?s Office. Aim 1: During the first two years of the study, we will examine the strategies associated with START implementation (penetration and fidelity) and service delivery outcomes (substance use assessment, timely access to treatment, number of sessions), given system and organizational features. We will conduct a convergent mixed methods study with the 17 counties and draw on worker surveys, administrator reports, administrative data, and group interviews. Data will be integrated and analyzed using Qualitative Comparative Analysis (QCA). Aim 2: In the second year of the study, we will develop a decision support guide to facilitate selection of collaborative strategies. An expert panel comprised of implementation experts, and stakeholders from the substance use treatment child welfare system will convene to synthesize findings from the literature and Aim 1, to specify a START implementation strategy. Aim 3: During the final stage of the study, we will assess the acceptability, appropriateness, and feasibility of the START implementation strategy. We will compare the feasibility of the decision support guide to general implementation supports from the perspective of child welfare agency directors from outside of the 17 county region, and pilot the decision support guide in up to 3 counties. The proposed research will lay the foundation for a future R01 application to test the decision making guide?s effectiveness in a larger scale-up initiative.